1. Field of the Invention
The present invention relates to a video editing method, and more particularly, to a video editing method of editing a time for displaying a message according to a calculated time variance of a video stream.
2. Description of the Prior Art
When conventional digital versatile discs (DVD) are used for displaying videos, information stored on the digital versatile discs includes a huge quantity of video streams and corresponding message-related information, i.e., subtitle information files. While displaying contents of a conventional digital versatile disc, a video stream stored on the conventional digital versatile disc is loaded first, then a corresponding message and a time for displaying the corresponding message are loaded from a subtitle information file to display the loaded video stream and the loaded message on a screen together. The subtitle information file may include conventional text or text bitmaps displayed in forms of images.
Sometimes, a user requires adding to, or deleting from contents of a video stream, and therefore the time stored in the subtitle information file for displaying the message is required to be shifted. However, since contents burned onto a conventional digital versatile disc cannot be modified, the subtitle information file stored on the conventional digital versatile disc cannot be directly edited by the user. The time for displaying the message may only be edited when both the video stream and the subtitle information file are copied onto a hard drive or another storage unit, in which the user may proceed with editing.
Conventionally speaking, there are two methods for the user to edit the subtitle displayed with the video.
In the first method, with the aid of a tool program, the user combines the video stream with the message, and then utilizes an additional video editing program for performing video editing. However, image quality of the combined video stream has been damaged so that an original image quality cannot be recovered. Moreover, if contents in the combined video stream have to be added or deleted, the user has to decode the combined video stream back to an original video stream and the message, and manually matches the time for displaying the message with the video stream according to the added or deleted contents to meet requirements of the user in displaying the proper message along with the video stream. Repeated encoding and decoding of the video stream are used in the first method so that the image quality of the video stream is significantly and repeatedly damaged as well.
In the second method, with the aid of a tool program, the user fetches the original video stream, which has not been combined with the message, and loads the original video stream into an image editing program. While using the image editing program, the user establishes the message to be displayed along with the video stream in the subtitle information file, and manually matches the established message with the accurate time for displaying the message according to desired requirements. In the second method, the user requires complicated steps for matching the displayed message with the accurate time or an accurate duration corresponding to the original video stream. Though the second method retains the image quality of the original video stream, precisely matching the displayed message with the accurate time is tiresome for the user.
In summary, the abovementioned methods result in repeated damage to the image quality of the video stream or a huge effort by the user in editing the time for displaying the message along with the video stream. These conditions bring significant inconveniences for the user while the user attempts to edit the video stream.